IStructuralEquatable IStructuralEquatable IStructuralEquatable IStructuralEquatable Interface

定義

定義支援物件之結構相等比較的方法。Defines methods to support the comparison of objects for structural equality.

public interface class IStructuralEquatable
public interface IStructuralEquatable
type IStructuralEquatable = interface
Public Interface IStructuralEquatable
衍生

範例

預設相等比較子, EqualityComparer<Object>.Default.Equals,會考慮兩個NaN相等的值。The default equality comparer, EqualityComparer<Object>.Default.Equals, considers two NaN values to be equal. 不過,在某些情況下,您可能想要的比較NaN值是否相等,傳回false,這表示無法比較值。However, in some cases, you may want the comparison of NaN values for equality to return false, which indicates that the values cannot be compared. 下列範例定義一個實作 NanComparer 介面的 IStructuralEquatable 類別。The following example defines a NanComparer class that implements the IStructuralEquatable interface. 它會比較兩個Double或兩個Single使用等號比較運算子的值。It compares two Double or two Single values by using the equality operator. 將任何其他類型的值傳遞至預設相等比較子。It passes values of any other type to the default equality comparer.

using System;
using System.Collections;
using System.Collections.Generic;

public class NanComparer : IEqualityComparer
{
   public new bool Equals(object x, object y)
   {
      if (x is float)
         return (float) x == (float) y;
      else if (x is double)
         return (double) x == (double) y;
      else
         return EqualityComparer<object>.Default.Equals(x, y);
   }
   
   public int GetHashCode(object obj)
   {
      return EqualityComparer<object>.Default.GetHashCode(obj);
   }
}
Imports System.Collections
Imports System.Collections.Generic

Public Class NanComparer : Implements IEqualityComparer
   Public Overloads Function Equals(x As Object, y As Object) As Boolean _
          Implements IEqualityComparer.Equals
      If TypeOf x Is Single Then
         Return CSng(x) = CSng(y)
      ElseIf TypeOf x Is Double Then
         Return CDbl(x) = CDbl(y)
      Else
         Return EqualityComparer(Of Object).Default.Equals(x, y)
      End If
   End Function
   
   Public Overloads Function GetHashCode(obj As Object) As Integer _
          Implements IEqualityComparer.GetHashCode
      Return EqualityComparer(Of Object).Default.GetHashCode(obj)
   End Function
End Class

下列範例會建立兩個相同的 3 元組物件,其元件包含三個Double值。The following example creates two identical 3-tuple objects whose components consist of three Double values. 第二個元件的值是Double.NaNThe value of the second component is Double.NaN. 此範例接著會呼叫Tuple<T1,T2,T3>.Equals方法,且其會呼叫IStructuralEquatable.Equals方法三次。The example then calls the Tuple<T1,T2,T3>.Equals method, and it calls the IStructuralEquatable.Equals method three times. 第一次,它會傳遞所傳回的預設相等比較子EqualityComparer<T>.Default屬性。The first time, it passes the default equality comparer that is returned by the EqualityComparer<T>.Default property. 第二次,它會傳遞所傳回的預設相等比較子StructuralComparisons.StructuralEqualityComparer屬性。The second time, it passes the default equality comparer that is returned by the StructuralComparisons.StructuralEqualityComparer property. 第三次,它會傳遞自訂NanComparer物件。The third time, it passes the custom NanComparer object. 如範例輸出所示前, 三個方法呼叫傳回true,而第四個呼叫會傳回falseAs the output from the example shows, the first three method calls return true, whereas the fourth call returns false.

public class Example
{
   public static void Main()
   {
      var t1 = Tuple.Create(12.3, Double.NaN, 16.4);
      var t2 = Tuple.Create(12.3, Double.NaN, 16.4);
      
      // Call default Equals method.
      Console.WriteLine(t1.Equals(t2));
      
      IStructuralEquatable equ = t1;
      // Call IStructuralEquatable.Equals using default comparer.
      Console.WriteLine(equ.Equals(t2, EqualityComparer<object>.Default));
      
      // Call IStructuralEquatable.Equals using 
      // StructuralComparisons.StructuralEqualityComparer.
      Console.WriteLine(equ.Equals(t2, 
                        StructuralComparisons.StructuralEqualityComparer));
      
      // Call IStructuralEquatable.Equals using custom comparer.
      Console.WriteLine(equ.Equals(t2, new NanComparer()));
   }
}
// The example displays the following output:
//       True
//       True
//       True
//       False
Module Example
   Public Sub Main()
      Dim t1 = Tuple.Create(12.3, Double.NaN, 16.4)
      Dim t2 = Tuple.Create(12.3, Double.NaN, 16.4)
      
      ' Call default Equals method.
      Console.WriteLine(t1.Equals(t2))
      
      Dim equ As IStructuralEquatable = t1
      ' Call IStructuralEquatable.Equals using default comparer.
      Console.WriteLine(equ.Equals(t2, EqualityComparer(Of Object).Default))
      
      ' Call IStructuralEquatable.Equals using 
      ' StructuralComparisons.StructuralEqualityComparer.
      Console.WriteLine(equ.Equals(t2, 
                        StructuralComparisons.StructuralEqualityComparer))
      
      ' Call IStructuralEquatable.Equals using custom comparer.
      Console.WriteLine(equ.Equals(t2, New NanComparer))
   End Sub
End Module
' The example displays the following output:
'       True
'       True
'       True
'       False

備註

結構相等表示兩個物件相等的因為它們有相同的值。Structural equality means that two objects are equal because they have equal values. 不同於參考相等,指出兩個物件參考相等的因為它們參考相同的實體物件。It differs from reference equality, which indicates that two object references are equal because they reference the same physical object. IStructuralEquatable介面可讓您實作自訂的比較,若要檢查的集合物件的結構是否相等。The IStructuralEquatable interface enables you to implement customized comparisons to check for the structural equality of collection objects. 也就是說,您可以在 建立您自己定義的結構是否相等,並指定可接受的集合類型會使用此定義IStructuralEquatable介面。That is, you can create your own definition of structural equality and specify that this definition be used with a collection type that accepts the IStructuralEquatable interface. 此介面有兩個成員: Equals,它會使用指定的測試是否相等IEqualityComparer實作,和GetHashCode,它會傳回相同的雜湊程式碼相等的物件。The interface has two members: Equals, which tests for equality by using a specified IEqualityComparer implementation, and GetHashCode, which returns identical hash codes for objects that are equal.

注意

IStructuralEquatable介面支援僅自訂比較的結構是否相等。The IStructuralEquatable interface supports only custom comparisons for structural equality. IStructuralComparable介面支援自訂的結構化比較來排序及順序。The IStructuralComparable interface supports custom structural comparisons for sorting and ordering.

.NET Framework 也提供預設的等號比較子,由EqualityComparer<T>.DefaultStructuralComparisons.StructuralEqualityComparer屬性。The .NET Framework also provides default equality comparers, which are returned by the EqualityComparer<T>.Default and StructuralComparisons.StructuralEqualityComparer properties. 如需詳細資訊,請參閱範例。For more information, see the example.

泛型的元組類別 (Tuple<T1>Tuple<T1,T2>Tuple<T1,T2,T3>等等) 和Array類別提供的明確實作IStructuralEquatable介面。The generic tuple classes (Tuple<T1>, Tuple<T1,T2>, Tuple<T1,T2,T3>, and so on) and the Array class provide explicit implementations of the IStructuralEquatable interface. 轉型 (在 C# 中),或轉換 (在 Visual Basic),因此目前的執行個體的陣列或 tupleIStructuralEquatable介面值,並提供您IEqualityComparer做為引數的實作Equals方法中,您可以定義自訂的等號比較比較陣列或集合。By casting (in C#) or converting (in Visual Basic) the current instance of an array or tuple to an IStructuralEquatable interface value and providing your IEqualityComparer implementation as an argument to the Equals method, you can define a custom equality comparison for the array or collection.

方法

Equals(Object, IEqualityComparer) Equals(Object, IEqualityComparer) Equals(Object, IEqualityComparer) Equals(Object, IEqualityComparer)

判斷物件與目前的執行個體在結構上是否相等。Determines whether an object is structurally equal to the current instance.

GetHashCode(IEqualityComparer) GetHashCode(IEqualityComparer) GetHashCode(IEqualityComparer) GetHashCode(IEqualityComparer)

傳回目前執行個體的雜湊碼。Returns a hash code for the current instance.

適用於

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